DTI Measurements in Multiple Sclerosis: Evaluation of Brain Damage and Clinical Implications

Abstract

Diffusion tensor imaging (DTI) is an effective means of quantifying parameters of demyelination and axonal loss. The application of DTI in Multiple Sclerosis (MS) has yielded noteworthy results. DTI abnormalities, which are already detectable in patients with clinically isolated syndrome (CIS), become more pronounced as disease duration and neurological impairment increase. The assessment of the microstructural alterations of white and grey matter in MS may shed light on mechanisms responsible for irreversible disability accumulation. In this paper, we examine the DTI analysis methods, the results obtained in the various tissues of the central nervous system, and correlations with clinical features and other MRI parameters. The adoption of DTI metrics to assess the outcome of prognostic measures may represent an extremely important step forward in the MS research field.

Figure 1

Elliptical representation of a diffusion tensor with the 3 main axes: the longest axis stands for the primary eigenvector (λ ₁), reflecting the diffusion parallel to the fibers; the two shorter axes represent the second (λ ₂) and third (λ ₃) eigenvectors, whose average provides a measure of diffusivity perpendicular to the fibers.

Figure 2

Three-dimensional tractography that reconstructs brain white matter bundles. The different colors represent different directions of the fibers.